Mark Christopher Fleming

Mark C. Fleming is a highly experienced patent appellate litigator and Co-Chair of WilmerHale's Appellate and Supreme Court Litigation Practice, where he has practiced his entire tracked patent litigation career. He primarily represents defendant operating companies, particularly in high-stakes appeals challenging large patent infringement judgments. His practice spans a diverse array of technology areas, including medical devices, life sciences, biotechnology, pharmaceuticals, semiconductors, smartphones, online storage and processing, and connectivity.

Mr. Fleming has an impressive record before the U.S. Court of Appeals for the Federal Circuit and the Supreme Court. He notably secured the vacatur of the largest patent infringement judgment in history, over $2.7 billion, for Cisco Systems in Centripetal Networks v. Cisco Systems (2022). In 2025, he achieved multiple significant victories within a single week at the Federal Circuit, overturning more than $500 million in damages for clients including Apple (in Optis Cellular Technology v. Apple, vacating a $300 million judgment) and PNC Bank (reversing a nearly $223 million judgment in United Services Automobile Association v. PNC Bank). Other prominent successes include the reversal of a $506 million judgment against Apple in WARF v. Apple (2019) and arguing and winning Stanford University v. Roche Molecular Systems (2011) before the Supreme Court, a key case on the Bayh-Dole Act. His appellate work also includes cases involving prenatal DNA testing technology (Verinata Health Inc. v. Ariosa Diagnostics Inc.) and computer server technology (Acceleron, LLC v. Dell Inc.).

Mr. Fleming is also involved in appeals stemming from post-grant proceedings, having secured the reversal of a PTAB decision invalidating a patent on a cancer drug in OSI Pharm., LLC v. Apotex Inc. (2019) and the affirmance of a PTAB decision invalidating claims as obvious in American Vehicular Sciences, LLC v. Unified Patents Inc. (2018). He was also a presenter on "Appeals from Post-Grant Proceedings" in 2014, and is counsel of record for Cisco Systems, Inc. in an application to extend time to file a petition for a writ of certiorari in a case involving the USPTO Director.

Mr. Fleming earned his JD, magna cum laude, from Harvard Law School in 1997 and his BA, with honors, from the University of King's College/Dalhousie University in 1994. He is admitted to practice in Massachusetts, the U.S. Supreme Court, and numerous Circuit Courts, including the Federal Circuit.